[Healeys] Parts

David Nock healeydoc at sbcglobal.net
Tue Jun 15 09:09:30 MDT 2010

We had a car here in the shop that had a problem after a brake  
rebuild. The pedal was always soft and no matter what we could not  
get a hard pedal. The owner was crippled in one leg and was very  
weak. What we found was the flex hoses were swelling when you pressed  
on the pedal. The cause of the swelling was that the attachment point  
of the master cylinder push rod had been re drilled about 1/2 higher.

Now the original pedal has a ratio of 4.89:1. So assuming 50lbs of  
pedal pressure at this ratio your actually on the master cylinder  
push rod is 245 lbs.  So if you move the attachment point up by 1/2  
inch the ratio is now 6.3:1. Now with 50 lbs of pedal pressure the  
applied pressure at the cylinder is 315 lbs.

So to get the same amount of applied pressure at the master cylinder  
with a ratio of 6.3:1 you will only need to apply 38 lbs at the pedal.

Now to move the attachment point you would need to remove the pedal  
and re drill a hole for the clevis attachment.

David Nock
British Car Specialists
Stockton Ca 95205


On Jun 14, 2010, at 5:32 PM, Mark LaPierre wrote:

> David,  this is a new concept for me.  First time I have heard this  
> idea. What do you mean by "moving
> the  rod up"?     Up where?       A lighter clutch pedal would make  
> a huge difference for me.
> While I have your ear,  are the brake and clutch master cylinders  
> suppose to be identical on a 60 BT7?
> Thanks,   Mark
> ----- Original Message ----- From: "David Nock"  
> <healeydoc at sbcglobal.net>
> To: "Fred Wescoe" <fredwescoe at gmail.com>
> Cc: <healeys at autox.team.net>
> Sent: Monday, June 14, 2010 5:37 PM
> Subject: Re: [Healeys] Parts
>> The clutch pedal ratio is 4.89:1. By moving the attachment point up
>> 1/4" now the ration is 5.5:1 and 1/2" the ratio jumps to 6.3:1
>> David Nock
>> British Car Specialists
>> Stockton Ca 95205
>> 209-948-8767
> : http://autox.team.net/mailman/options/healeys/ 
> lapierrem at sbcglobal.net

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